1. Technical Field
The embodiments disclosed herein generally relate to Session Initiation protocol (SIP) functionality, and, more particularly, to a method for enhancing SIP functionality to integrate media capabilities of end terminals.
2. Description of the Related Art
There are many high-end phone terminals (Session Initiation Protocol (SIP)/IP. Media Subsystems (IMS) hardphones, softphones, cellular phones and so on) available in market. There exists no mechanism for a relatively unsophisticated terminal to have extra functions to be devolved to other capable terminals. For example, a calling terminal, terminal A with audio and video capabilities cannot perform the task of video exchange with the called terminal, terminal B which has audio capability but does not have video capability, and, in no way (at present), terminal B can devolve the task of video exchange to another video-capable terminal. Hence, it is not possible to aggregate media capabilities of various unsophisticated terminals and converse with high-end terminals.
The Session Initiation Protocol (SIP) exploits an application-level control protocol for setting up, changing and terminating multimedia sessions between participants on IP data networks. SIP can enable a range of services, such as Internet telephony, multimedia conferencing, registration and redirection services, simplifies connecting to VPNs, etc.
Generally, SIP functionality might not allow redirection of some particular type of media to other terminals. For instance, there can be two sessions at terminal A, one between A and B and the other between A and C. But present SIP terminal implementations treat the two sessions originating from terminal A as two different sessions. Thus, media sharing between two sessions is not possible and hence the sessions need to be switched i.e. one session at a time can only use the media I/O of the terminal.
Session Description Protocol (SDP) negotiation is a solution put forward to address the problem of media sharing. Usually, SDP negotiation is implemented on behalf of a terminal (for example, terminal C) and this implementation requires prior knowledge of IP address of the terminal to which selected media need to be redirected. For example, if terminal B is assured that terminal C can handle SDP, then terminal B can respond to terminal A, including the SDP for terminal C.
However, the aforementioned method has the drawback of limiting the mobility of the user. A further drawback of the aforementioned method is that the IP address of an allocated terminal may change frequently. Also, it is not possible for multiple SIP terminals to receive the same media simultaneously. Furthermore, an application server infrastructure needs to be installed for signaling on behalf of a terminal.